The present invention discloses apparatus for measuring the distance between a metal workpiece and an arc welding torch, and more particularly, apparatus for using an electric arc for measuring the work distance.
In order to facilitate the automatically controlled welding of metals, such as aluminum, it is necessary to sense the location of a weld groove and to guide an electric welding torch in the weld groove. Such sensing of the groove includes measuring the distance between the welding torch and the workpiece and sensing changes in this work distance to determine the presence and direction of a groove as the welding torch moves along a path substantially parallel to the surface of the workpiece.